Originally Posted by snoopyrc
Thats what he means. Tinning is to melt some solder onto the ends of each battery bar and also to the ends of the cells.
...and the end of the iron as well!
This makes soldering easy with two hands as you don't have to have a third hand to hold the spool of solder. Simply touch the freshly tinned iron to the one or both of the tinned items, and all the solder in the area quickly melts & flows together making a perfect joint!!!